“Major problems” can include death. In Feb. 2011, a 20-year-old British woman died in Philadelphia after getting a bargain-basement buttock enhancement procedure in her hotel room. Just weeks before, 36-year-old Whalesca Castillo was arrested for operating without a license and injecting women’s breasts and buttocks with liquid silicone from her home in the Bronx. She was sentenced to a year in prison after pleading guilty this past June.

In July, Oneal Ron Morris of Miami was charged with manslaughter in the death last March of Shatarka Nuby, 31. Morris was already facing charges of practicing health care and without a license and causing serious bodily injury for allegedly injecting at least two women with a toxic mixture of Fix-a-Flat tire sealant, mineral oil and cement in a backroom attempt at buttock enhancement. Nuby died after receiving injections to enlarge her breasts, allegedly from Oneal.

The American Society for Aesthetic Plastic Surgery has a long list of such incidents. “Disturbing reports of patients being injected with everything from liquid silicone to baby oil and other unapproved products are appearing in the press on a regular basis," the group says on its website. "Make sure your clinician is using only FDA-approved products purchased within the United States. If he or she refuses to give you this information, seek another clinician.”

Gluteal enhancement – known colloquially as “butt implants” -- are among the more unusual cosmetic procedures that people ask for but are becoming more common, according to the American Society for Plastic Surgeons.

Its data shows that in 2011, 1,149 people got buttock implants, compared to 806 in 2010. There are no statistics for earlier years. That compares to 4,546 people who got buttock lifts in 2011, and 301,000 who got breast augmentation. The American Society for Aesthetic Plastic Surgery counted 2,100 buttock augmentation procedures in 2004.

When so many people are trying to lose weight, why the pursuit of a larger derriere? “It really started with J-Lo,” says Youn. Singer Jennifer Lopez is known for her curves – especially her shapely bottom. “Part of it is cultural, I think,” added Youn. “We have a popular culture that puts an emphasis on the size of the buttocks.”

He points to Kate Middleton’s younger sister Pippa, whose profile in a tight dress grabbed attention at Middleton’s 2011 wedding to Britain’s Prince William -- but the phenomenon goes back even farther, to Sir Mix-a-Lot’s 1992 hit “Baby Got Back,” which starts with the line “I like big butts”.

For people who want such enhancements, it’s important to go to a professional with a lot of experience, Youn says. Board certified plastic surgeons are members of the American Society for Plastic Surgeons or the American Society for Aesthetic Plastic Surgery, or both. “And you want to make sure they do a lot of these every year. It’s not for the novice doctor,” Youn advises.

Youn says he won’t do buttock implants, but will inject fat to enhance various body areas. A lot can go wrong, he said.

“One reason it is fraught with complications is the area where you put the implant, we consider it a dirty area,” Youn said. “Implants, if they get any type of bacteria on them, can get infected very easily.”

And that can cause a complication no one wants. “When implants get infected they can literally extrude. The body can open the incision and try to push it back out,” he said.

Second, the gluteus maximus is the largest muscle in the body, and needs big blood vessels to supply it. If silicone gets into the blood, it can cause embolisms, which are painful and potentially deadly if they end up in the heart or brain.

The operation itself isn’t fun. “It is a painful operation because you have to sit on that area,” Youn said. “You have to literally avoid sitting on your bottom for weeks afterward.”

Or something might happen like the YouTube video shows.

“If the pocket that the implant was put in is too big, then the implant will move around like that,” Youn says. “I have seen it with breast implants. You can literally flip the implant around in your breast.”

Buttock implants are shaped with one rounded side and one flat side, Youn said, “You want to put it in the buttocks like a hand in a glove where it really doesn’t move.”